1. Field of the Invention
The present invention relates to an activity meter that measures an amount of physical activity of a user, and more particularly to an activity meter that outputs an index relating to the amount of physical activity.
2. Description of the Related Art
For activity meters, JP 2006-204446A and JP 2001-258870A describe methods for measuring the exercise intensity of physical activity or the calories burned during physical activity utilizing an acceleration sensor. With the activity meter of JP 2006-204446A, a standard deviation Sw of acceleration in a fixed time period tw is computed from the output signal of the acceleration sensor, and an exercise intensity wi is computed from the standard deviation Sw using a conversion equation formulated in advance. Also, with the device of JP 2001-258870A, the impulse of momentum is calculated by vector synthesis from tri-axial acceleration, and energy expenditure is calculated from the impulse in response to the type of exercise. The type of exercise is determined based on the ratio of the impulse calculated by vector synthesis and the impulse in the depth, horizontal and vertical directions.
In JP 2010-17525A, whichever age activity pattern that the user's state of activity is equivalent to is computed by comparing the energy expenditure history with reference data.
There are calls among users of activity meters for an index of the amount of physical activity to be presented in comparison with other users, to avoid becoming complacent about the amount of physical activity they do. In this regard, although the activity meters of JP 2006-204446A and JP 2001-258870A output the user's activity amount as calories burned, it is unclear whether the amount of calories burned is high or low or to what age group that amount of calories burned is equivalent.
Although the age activity pattern to which the user's state of activity is equivalent is computed in JP 2010-17525A, an index relating to activity for attaining a target activity pattern is not presented.